Abstract
The impact of configurational entropy, enthalpy, and strain energy on the phase stability of high-entropy materials has not yet been investigated quantitatively. We used ab-initio calculations to predict the driving force for decomposition of 126 equimolar Al-containing high-entropy sublattice nitrides (HESN), which are all metastable with respect to all corresponding equimolar lower-entropy nitride phases. The entropy stabilization of ≈−0.06 eV/at. at 1073 K is overruled by the 0.10-0.27 eV/at. enthalpy-governed driving force for decomposition. Stabilization is however predicted for 22 compositions due to the −0.01 to - 0.28 eV/at. strain energy contribution caused by large differences in equilibrium volume between the HESN and their decomposition products. The predicted stabilities are consistent with diffraction and tomography data of annealed nitride coatings. Hence, it is evident that only strain enables the stabilization of the here studied Al-containing HESN, while the entropic contribution is overruled by endothermic mixing.
| Originalsprache | Englisch |
|---|---|
| Aufsatznummer | 117483 |
| Seitenumfang | 14 |
| Fachzeitschrift | Acta materialia |
| Jahrgang | 224.2022 |
| Ausgabenummer | 1 February |
| Frühes Online-Datum | 2 Dez. 2021 |
| DOIs | |
| Publikationsstatus | Veröffentlicht - 1 Feb. 2022 |
Bibliographische Notiz
Funding Information:This work was funded by the Austrian COMET Program (project K2 InTribology, no. 872176). The computations have been performed at the Vienna Scientific Cluster (VSC). J.M.S. gratefully acknowledges funding by Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Center SFB-TR 87/3 “Pulsed high power plasmas for the synthesis of nanostructured functional layers”. The authors acknowledge the use of the X-ray center at TU Wien. Plansee Composite Materials GmbH is acknowledged for supplying target materials. The authors acknowledge TU Wien Bibliothek for financial support through its Open Access Funding Programme.
Publisher Copyright:
© 2021 The Author(s)
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